Tracking the longitudinal course of physiologic and mental health functioning among individuals in substance use disorder treatment

Introduction Mental health monitoring is crucial to long-term recovery in substance use disorder (SUD) treatment; however, little is known about how changes in physiological indicators align with changes in self-reported mental health over time. Methods We examined longitudinal associations of resting heart rate (RHR) and heart rate variability (HRV) collected via a WHOOP® photoplethysmography device with self-reported stress, anxiety, and depressive symptoms among individuals in SUD treatment. Participants ( N = 59) continuously wore the device and completed at least two mental health and stress assessments during the first month of residential treatment. Results Linear regression results indicated favorable changes in mental health and/or physiologic metrics, with notable heterogeneity in concurrent subject-level trends. Among participants with decreased RHR (better physiological functioning), 39% ( N =23) also endorsed decreased stress, 42% ( N =25) decreased anxiety, and 39% ( N =23) improved depressive symptoms. Of those with increased HRV (greater stress adaptability), 39% ( N =23) endorsed decreased stress, 39% ( N =23) improved anxiety, and 41% ( N =24) reduced depressive symptoms. Discussion Concurrent changes in physiologic and mental health metrics during the first month of treatment varied across participants. These findings highlight the importance of integrating subjective mental health measures with physiological indicators to capture clinically relevant change during early SUD treatment.